1. Field of the Invention
The present invention relates to an apparatus and a method for controlling operation of a linear compressor which are capable of operating a linear compressor by being inputted a stroke reference value, and in particular to an apparatus and a method for controlling operation of a linear compressor using a pattern recognition which are capable of operating a linear compressor as an optimum efficiency by recognizing relation between a current and a displacement as a pattern.
2. Description of the Prior Art
Generally, a function of a compressor pressurizes a refrigerant vapor to help easier condensing of the refrigerant vapor evaporated in an evaporator. By the operation of the compressor, a refrigerant transports heat from a cold place to a hot place by repeating condensing and evaporating processes while circulating through a refrigerating apparatus.
Recently, various types of compressors are used, and a reciprocating compressor is used in general. The reciprocating compressor uses a method rising a pressure by pressurizing vapor by a piston moving up and down inside a cylinder, particularly when the reciprocating compressor is used for a refrigerator or an air conditioner, a compression ratio can be varied by varying a stroke voltage applied to the reciprocating compressor, accordingly it is advantageous to a variable refrigerating capacity control.
However, because the reciprocating compressor compresses vapor by converting a rotation motion of a motor into a linear motion, mechanical converting apparatus such as a screw, a chain, a gear system and a timing belt, etc. for converting the rotation motion into the linear motion are essential. Accordingly, because energy loss due to the conversion is large and a structure of the apparatus is intricate, recently a linear compressor using a linear method in which a motor itself performs a linear motion is used.
The linear compressor does not require mechanical converting apparatus by directly generating a linear operation force by a motor itself, has a simple structure, reduces loss due to energy conversion and largely decreases a noise by not including a connection portion caused friction and abrasion. In addition, when the linear compressor is used for a refrigerator or an air conditioner, a compression ratio can be varied by varying a stroke voltage applied to the linear compressor, accordingly it is advantageous to a variable refrigerating capacity control.
FIG. 1 is a block diagram illustrating a construction of an apparatus for controlling operation of a linear compressor in accordance with the conventional art. As depicted in FIG. 1, an apparatus for controlling operation of a linear compressor includes a linear compressor 3 adjusting a refrigerating capacity by varying a stroke (a distance between a top dead center and a bottom dead center of a piston) with a reciprocating motion of a piston by a stroke voltage, a current detecting unit 5 detecting a current applied to the linear compressor 3 by the variation of the stroke, a voltage detecting unit 7 detecting a voltage generated in the linear compressor 3 by the variation of the stroke, a microcomputer 9 calculating a stroke by using the current and the voltage detected from the current detecting unit 5 and the voltage detecting unit 7 and outputting a switching control signal by comparing the calculated stroke with a stroke reference value inputted by a user, and an electric circuit unit 1 intermitting AC power by the outputted switching control signal and applying a stroke voltage to the linear compressor.
The control operation of the conventional linear compressor will be described.
First, by the stroke reference value set by the user, the electric circuit unit 1 outputs a stroke voltage, the piston performs a linear motion by the stroke voltage, according to it the stroke (a distance between a top dead center and a bottom dead center) is varied, accordingly the refrigerating capacity of the linear compressor 3 is controlled.
In more detail, in the linear compressor 3, the stroke is varied by the linear motion of the piston of the cylinder, the refrigerating gas inside the cylinder is transmitted to a condenser through a discharge valve, accordingly the refrigerating capacity is adjusted.
Herein, when the stroke is varied by the stroke value, the current detecting unit 5 and the voltage detecting unit 7 detect the voltage and the current generated in the linear compressor 3, and the microcomputer 9 calculates the stroke by using the detected voltage and the current.
In addition, when the calculated stroke is smaller than the stroke reference value, the microcomputer 9 increases a stroke voltage applied to the linear compressor 3 by outputting a switching control signal lengthening an on cycle of a triac, as described, when the calculated stroke is larger than the stroke reference value, the microcomputer 9 outputs a switching control signal shortening an on cycle of triac, accordingly the stroke value applied to the linear compressor 3 is decreased.
However, because the conventional apparatus has a serious non-linearity in the mechanical motion characteristics, it is impossible to perform a precise control with the linear control method not considering the non-linearity.
Accordingly, it is an object of the present invention to provide an apparatus and a method for controlling operation of a linear compressor using a pattern recognition which are capable of controlling a TDC (top dead center) by considering an error due to non-linearity characteristics and improving an operation efficiency of a linear compressor.
In order to achieve the above-mentioned object, an apparatus for controlling operation of a linear compressor includes a current detecting unit 20 detecting a current applied to a linear compressor, a voltage detecting unit 30 detecting a voltage generated in the linear compressor, a displacement calculating unit 40 calculating a displacement by being inputted the current detected in the current detecting unit and the voltage detected in the voltage detecting unit, a pattern recognition unit 50 being inputted the displacement outputted from the displacement calculating unit and the current outputted from the current detecting unit and detecting a pattern by using a trace corresponded to the displacement and the current, a stroke controlling unit 60 being inputted a pattern from the pattern recognition unit 50 and outputting a switching control signal according to the inputted pattern, and an electric circuit unit 10 being inputted the switching control signal outputted from the stroke controlling unit 60 and outputting a certain voltage to the linear compressor 11.
In order to achieve the above-mentioned object, a method for controlling operation of a linear compressor includes detecting a current and a voltage generated in the operation of the linear compressor 11, calculating and outputting a displacement by using the detected current and the voltage, detecting a pattern by using a trace corresponded to the calculated displacement and the detected current, comparing the detected pattern with a reference pattern and outputting a switching control signal when they coincide with each other, and operating the linear compressor 11 by applying the stroke voltage to the linear compressor according to the switching control signal.